This invention relates to the general field of child-resistant containers for medicines, and the like, and particularly to the field of medicine vials in which pharmacists dispense tablets, pills, capsules, etc.
Possibly the most widely used type of child-resistant medicine vial consists of a tubular open topped container, usually molded from a transparent or semi-transparent resinous material, with circumferentially spaced, bayonet type threads on its exterior, these threads being located at a level a little distance below the open top of the container. The cap for this type of medicine vial has a disc-like top and a single skirt which fits circumjacent to the open end of the container and has a plurality of inwardly directed lugs which are engaged in the bayonet threads of the container by rotating the cap relative to the container. In order to secure the cap on the container against its being loose or lost, the cap usually has a flexible disc in its interior and the underside of the cap top has a central protrusion over which the perimeter of the disc is bent upwardly when the cap is thrust downwardly on the container and rotated so that the cap lugs snap into the bayonet threads on the container. The disc is flexible and is biased to thrust the cap upwardly, maintaining a tight engagement between the sets of cooperating threads and lugs.
While this type of medicine vial is widely used, it consists of three separate parts, viz: the container, the cap and the flexible disc. Thus, to manufacture these vials it is necessary to have two multi-compartment molds for the container and cap and a separate mechanism for punching out the flexible biasing discs. The discs must either be hand assembled in the caps or an additional piece of complex equipment is necessary to mechanically insert the discs into the caps.
Other types of child-resistant medicine vials have been suggested, for examples those shown in U.S. Pat. Nos. 3,372,834 to Ayotte, et al and 3,759,411 to Horvath. In both of these prior art patents, the cap and containers have cooperating lugs and ramps so that when the caps are rotated relative to the containers the edges of the caps are lifted or spaced away from the containers so that they can be grasped by the fingernail of the user and removed. However, this action results merely from rotation of the caps and containers relative to each other.
It has been found that the degree of child-resistance in a container and cap combination is greatly improved if removal requires two different movements. If the cap can be removed merely by rotation, a small child frequently will bite the cap between its teeth and turn the container relative to the cap. In both of the prior art patents mentioned above this would result in opening the container and giving the child access to its contents. This would defeat the very purpose of endeavoring to make the container child-resistant.